Unitized regenerative PEMfuel cell stack improvement

In this study, the Unitized Regenerative PEM Fuel Cell (UR-PEMFC), which can operate in both electrolyzer and fuel cell modes, is investigated experimentally and theoretically. In the theoretical study, a 3D mathematical model has been developed for the heat and mass transfer, flow and chemical reactions occurring in UR-PEMFC. The model, which includes the transition to two-phase flow and the behavior of the phases depending on the process parameters, was solved numerically and validated with experimental data. Within the scope of experimental studies, firstly cells with an active area of 5 cm2 were tested, using the optimized results here, they were transported to industrial sizes (100 cm2) and then turned into a stack. In order to increase the performance of the system, optimum flow and heat transfer conditions have been examined and it has been seen that the effect of temperature and bolt number on performance is significant compared to other process parameters. Optimum parameters were determined such as material selection, thickness, compression force, sealing elements and number of bolts used for UR-PEMFC components. With the modification studies on commercially purchased reversible membran electrode assembly (MEA), 17.13% in the electrolyzer mode and 16.98% in the fuel cell mode in a 100 cm2 single cell; for stack an improvement of 16,96% in the electrolyzer mode and 16,81% in the fuel cell mode was achieved.